CA2126285C - Preparation of isocyanurate-and/or uretdione-containing polyisocyanates having a reduced color index and improved shelf life, and products prepared by this method - Google Patents
Preparation of isocyanurate-and/or uretdione-containing polyisocyanates having a reduced color index and improved shelf life, and products prepared by this methodInfo
- Publication number
- CA2126285C CA2126285C CA002126285A CA2126285A CA2126285C CA 2126285 C CA2126285 C CA 2126285C CA 002126285 A CA002126285 A CA 002126285A CA 2126285 A CA2126285 A CA 2126285A CA 2126285 C CA2126285 C CA 2126285C
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- CA
- Canada
- Prior art keywords
- acid
- oligomerization
- uretdione
- peroxycarboxylic acid
- isocyanurate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/77—Polyisocyanates or polyisothiocyanates having heteroatoms in addition to the isocyanate or isothiocyanate nitrogen and oxygen or sulfur
- C08G18/78—Nitrogen
- C08G18/79—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
- C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
- C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
- C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
- C07D251/30—Only oxygen atoms
- C07D251/34—Cyanuric or isocyanuric esters
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Polyurethanes Or Polyureas (AREA)
Abstract
Abstract of the Disclosure: Isocyanurate- and/or uretdione-containing polyisocyanates having a reduced color index and improved shelf life are prepared by conventional catalytic oligomerization of aliphatic and/or cycloaliphatic diisocyanates and treatment of the oligomerization products with peroxycarboxylic acids.
Description
~126~85 ~ O.Z. OOS0/44130 -Pre~aration of isocYanurate- and/or uretdione-containin~ PolYisocyanate~ havin~ a reduced color index and im~rovod shelf l~fe, and ~roducts PrePared by this method The present invention relates to a process for the preparation of isocyanurate- and uretdione-cont~;ning polyisocyanate mixtures having a reduced color $ndex by catalytic oligomerization of aliphatic and/or cyclo_ aliphatic diisocyanates and subsequent removal of the unconverted diisocyanates. The present invention fur-thermore relates to the products prepared by this process.
For high quality one-component and two-component polyurethane finishes having high light stability and weather stability, the isocyanate components used are in particular isocyanurate- and uretdione-conta~n~ng poly-isocyanate mixtures.
These products are preferably prepared by catal-ytic oligomerization of aliphatic and/or cycloaliphatic diisocyanates, eg. 1-isocyanato-3,3,5-trimethyl-5-iso-cyanatomethylcyclohexane (IPDI) orl,6-diisocyanatohe~Ane (HDI).
The catalysts used may be, for example, hydrox-ides or organic salts of weak acids having tetraalkyl-ammonium groups, hydroxides or organic salts of weakacids having hydroxyalkylammonium groups, alkali metal salts or tin, zinc or lead salts of alkanecarboxylic acids.
The aliphatic and/or cycloaliphatic diisocya~ates are allowed to react i~ the presence of the catalyst, with or without the use of solvents and/or assistants, until the desired conversion has been reached. There-after, the reaction is stopped by deactivating the catalyst and the excess mon~e~ic diisocyanate 18 dis-tilled off. Depending on the catalyst type used and onthe reaction temperature, polyisocyanates having dif-ferent contents of isocyanurate and uretdione groups are ~1 2~,?8 ,:-1 - ~ - 2 - O.Z. 0050/44130 obtained.
The products thus prepared are generally clear products wh$ch,~however, depsn~;n~ on the catalyst type, the diisocyanate guality, the reaction temperature and the reaction procedure, are more or less strongly yellow.
~ owever, products having a very low color index are desirable for the production of high quality poly-urethane finishes. The prior art discloses a number o~
methods for reducing tho color index of such products.
For example, DE-A-38 06 276 proposes reducing the carbon dioxide content of the HDI used as a monomer to less than 20 ppm before the oligomerization by degassing under reduced pressure and subsequently blowing nitrogen through the HDI, and using a quaternary ammonium hydrox-ide as the oligomerization catalyst. The process step of carbon dioxide removal is, however, technically very complicated.
EP-A-0 339 396 proposes the use of a quaternary ~on; um fluoride as a trimerization catalyst. In this process, a higher carbon dioxide content can be tolerated but the proposed catalyst must be chemically deactivated.
The resulting compounds remain in the product and may give ri~e to problems with performance characteristics during further processing. A further possibility for the preparation of isocyanurate-containing polyisocyanates having a lower color index is to add polyesterdiols to the starting diisocyanate, as proposed in EP-A-0 336 205.
This makes it possible to reduce the amount of catalyst u~ed. ~owever, the resulting products still have a relatively strong color.
In EP-A-0 377 177, the aliphatic diisocyanate is oligomerized in the presence of a phosphine as a catal-yst, and the unconverted diisocyanate is partly distilled off after the oligomerization has been stopped and partly converted into urethane by the addition of alcohol. The reaction product is then treated with peroxides.
Although the peroxide treatment results in a reduction in th~ color index of the oligomerization product, the use of peroxldec often gives riso to problem~. For example, peroxides aro technically dlfficult to h~n~le. Perox~des which aro safer to handlo are generally availablQ in solution, dibutyl phthalate, ~requently used as a sol-vent, then leading to pro~lems with the performance characteri~tics dur~ng production o~ the fin~h.
A ~urther substantial disad~antage of the prio~
art process i8 that the shelf life of the product~ thus o obtained i8 insufficient. The color properties deter~or-ato and in part~cular ther~ i8 a substantial increase in the ~i~cosity.
It iB an ob;ect of th~ present invention to pro~ide a simple proces~ for th~ preparation of i~ocyanurate- and/or uretdione-cont~n~ng polylsocyanates ha~ing a reduced color index, which proces~ a~oids the disadvantage~ of the prior art and in parti~ular lQads to products having an improved shel~ life.
In accordance with the invention, this object is 20 surprisingly achieved by a process for the preparation of an isocya-nurate- or uretdione-containing polyisocyanate having a reduced color index and improved shelf life comprising oligomerization of aliphatic or cycloaliphatic diisocyanates using oligomerization catalysts comprising hydroxides or organic salts of acids having tetraalkylammonium or hydroxy-alylammonium groups, alkali metal salts, or tin, zinc, or lead salts of alkanecarboxylic acids, and subsequently neutralizing said oligomerization catalyst with a peroxycarboxylic acid.
The present invention furthermore relates to the 30 isocyanurate- and/or uretdione-containing polyisocyanates having a reduced color index and prepared by this process.
When basic, in particular amine, oligomerization catalysts are used, peroxycarboxylic acids are added to deactivate the catalyst when the desired degree of oligomerization has been reached, and the oligomerization - 3a -product is then worked up in the conventional manner used in the prior-art, by removal of monomers, generally under greatly 212~85 4 - O.Z. 0050/44130 evaporator. A special process step for lightening the oligomerization products is then no longer required.
The oligomerization of the aliphatic and/or the cycloaliphatic diisocyanates i8 carried out by the method S usual ln the prior art.
The starting diisocyanates used are aliphatic and/or cycloaliphatic diisocyanates, eg. 1,4-diiso-cyanatohexane, 1,6-diisocyanatohexane (EDI), 1,12-diiso-cyanatododecane, l-isocyanato-3,3,5-trimethyl-5-iso-cyanatomethylcyclohexane (IPDI), 4,4'-di~socyanato-dicyclohexylmethane, 1,5-diisocyanato-2,2-dimethyl-pentane, 1,5-diisocyanato-2-ethyl-2-propylpentane, 1,6-diisocya~ato-2,4,4-trimethylhexane and l,S-diisocyanato-2-methylpentane, in particular EDI.
The oligomerization of the diisocyanates is preferably carri-d out at from 0 to 100~C by passing through inert gas, preferably nitrogen. The reaction rate is too low at lower temperatures, while the level of secondary reactions is greater at higher temperatures.
The catalysts used may be any catalysts suitable for the oligomerization of aliphatic and/or cyclo-aliphatic diisocyanates, for example hydroxides or organic salts of weak acids having tetraalkylammonium groups, hydroxides or organic salts of weak acids having hydroxyalkyl~ -n;um groups, alkali metal salts or tin, zinc or lead salts of alkanecarboxylic acids. The catalysts are usually used in an amount of from O.OS to 2% by weight, based on the diisocyanate.
To reduce the amount of catalyst, it is possible to add a small amount, up to about 1% by weight, based on the diisocyanate, of a diol, in part~cular a polyester-diol, to the diisocyanates in a manner ~nown per se, prior to oligomerization.
Thereafter, the diisocyanatQ is brought to the reaction temperature with stirring and the catalyst i8 slowly added. To improve the handling, the catalyst may be dissolved in a solvent. For example, alcohols, in 212~2~5 ~- - 5 - O.Z. 0050/44130 particular diols, ketono~, ethers and esters are suitable for this purpose.
After the desired conversion has been reached, the reaction is stopped by deactivation of the catalyst, for example by the addition of a catalyst poison or by thermal decomposition of the catalyst. The reaction mixture iB then freed from the monomeric diisocyanates in a suitable manner known per se, for example by distilla tion, eg. by means of a thin-film evaporator.
A particularly advantageous and therefore prefer-red e~hodiment of the invention comprise~, as stated above, using the peroxycarboxylic acids as neutralizing agentJ for the basic oligomerization catalysts employed.
The novel peroxycarboxylic acids are added to the reac-tion mixture in an amount of from 10 to 10,000 ppm, prefer~bly from 50 to 1,000 ppm, based on the reaction mixture, when the desired degree of oligomerization has been reached, in order to deactivate tho catalyst and hence to stop the reaction. The peroxycarboxylic acids may al~o be used together with conventional neutralizing agents. The reaction mixture is then freed from the monomeric diisocyanates in a suitable manner known per se, for example by distillation, eg. by means of a thin-film evaporator.
For the purposes of the present invention, it is, however, also possible to deactivate the catalyst in another suitable manner, for example by means of catalyst poisons or by thermal decomposition, when the desired degree of oligomerization has been reached. The reaction mixture i8 then freed from the monomeric diisocyanates in the manner described. The novel peroxycarboxylic acids are added in an amount of from 10 to 10,000 ppm, prefer-- ably from 50 to 1,000 ppm, based on the amount of diiso-cyanate, to the solution worked up in this manner.
The peroxycarboxylic acids used may be aromatic, aliphatic, cycloaliphatic, unsubstituted or substituted peroxycarboxylic acids. It is also possible to use 8 ~
_ - 6 -acidic salts of these peroxycarboxylic acld~.
Examples of peroxycarboxylic acids aro peracetic acid, peroxymaleic acld, tert-butyl peroxymaleia acld, perbenzoic acid, p-nitroperbenzoic acid peroxyphthalic a~
and in particular 3-chloroperbenzoic acid. Ammonium or magne~lum ~alt~ are used in partiaular as acldic salt~ o~
the peroxycarboxylia acid~.
ThR no~cl process ~or the preparatlon of i80-cyanurate- and/or uretdione-cont~n~ng polyisocyanatQ~
lQads to products having low color lndices. Th~ color lndlce~ are below 50 HAZEN but generally below 30 ~A~EN.
~owe~er, the particular advantago o~ the product~ pre-pared according to the lnvention is thelr very good shel~
li~e. Even after a storage! timQ o~ 6 month~ under a nltrogen atmosphere, there was no change in the color, and furthermore the iLcrea~e in the ~scoslty of these products was corre~ponding smaller than ~n the case of those which had been prepared by the prior art processe~.
An addit~onal ad~antageous ef~ect occurred 1~ the neutralization of tho oligomerization catalyst with peroxycarboxyl~c acld~. Here, the monomeric diisocyanate dlstilled o~f after the oligomerization o~ the al~phatic and/or cycloallphatic diisocyanates did not exhibit the disad~antage~ otherwise ~requently encountered in the ca~e o~ the corre~ponding products o~ the~ prlor art processen.
While, in thQ nQutralization o~ tho ollgomQriza-tion catalyst with the al~yl phosphate~ generally used 1~
the prior art proce~se~, the reactivlty o~ the recycled di~socyanate monomers wa~ substantlally lower than that o~ fresh diisocyanate and it i~ there~ore nece~sary ~o use a larger amount o~ cataly~t, the monomerlc dilso-cyanate recycled in the neutralization of the ol~gomerlz-ation catalyst with peroxycarboxyliQ acid~ exhlblted no such behavior and could be readily ol~gomQr~zQd unde~ the con~entional proce~s conditione and wlth the U8Q o~ the u~ual amount o~ ca~alyst.
2~'~62~5 - 7 - O.Z. 0050/44130 _ In the thermal decomposition of the oligomeriza-tion product, likewise known from ths prior art, the recycled monomer$c diisocyanate generally exhibits no differences in reactivity compared with fresh diiso-cyanato, but gelling of these products freguently occurs.
Furthermore, such behavior was not observed in the case of ths mon~ric diisocyanate8 obtained by the novel process.
The novel products are generally used a~ iso-cyanate components in polyurethane one-component and two-component finishes.
The Examples which follow illustrate the invention.
EXAMPLE 1 (Cn~rarison) 500 g of 1,6-diisocyanatohexane (EDI) were heated to 80~C under a nitrogen blanket, and 400 ppm of N,N,N-trimethyl-N-(2-hydroxypropyl)-a onium 2-ethylhexanoate, dissolved in 2 ml of methyl ethyl ketone (MER), were added while stirring.
When the NC0 content of the reaction mixture was 43% by weight, 2 mol eguivalents, based on tho amount of catalyst, of dibutyl phosphato were added and stirring was continued for 1 hour at 80~C. ~nconverted ~DI was then stripped off under greatly reduced pressure by means of a thin-film evaporator.
The color index of the oligomerized EDI was 78 HAZEN. 400 ppm of N,N,N-trimethyl-N-(2-hydroxypropyl)-a on; um 2-ethylhexanoate were then added, while stir-ring, to 250 g of the monomeric HDI stripped off. No decrease in the NC0 content was observed.
EXAMPLE 2 (Comparison) The procedure was as in Example 1, except that the reaction mixture was heated for 15 minutes at 110~C
to deactivate the catalyst.
The mon~ ~ric ~DI stripped off had a normal reactivity but gelled on stan~ing in a closed vessel under nitrogen at 5~C.
~2~2~
8 - O.Z. 0050/44130 EXAMPL~ 3 The procedure was as in Example 1, except that 2 mol equivalents, based on the catalyst, of 3-chloro-perbenzoic acid were used to neutralize the catalyst.
The color $ndex of the oligomerization product was 25 EAZEN. 400 ppm of N,N,N-trimethyl-N-(2-hydroxy-propyl) _r ~n~ um 2-ethylhexanoate, dissolved in 2 ml of MER, were added at 80~C to 200 g of the monomeric HDI-stripped off.
The decrease in the NCO content was the same as for fresh ~eno~ric HDI. When an NCO content of 43% by weight, based on the reaction mixture, had been reached, the catalyst wa~ neutralized by D~ ng 2 mol equivalents of 2-chloroperbenzoic acid. The oligomerization product had a color index of 20 EAZEN. 50 g of the monomeric HDI
stripped off were stored at 5~C for 4 weeks under nitrogen in a closed vessel. No gel formation occurred.
The procedure was as in Example 1, except that 2 mol equivalents of 4-nitroperbenzoic acid were used to neutralize the catalyst. The color index of the oligo-merization product was 27 HAZEN.
The procedure was as in Example 1, except that 2 mol equivalents of magnesium monoperoxyphthalate were used to neutralize the catalyst. The color index of the oligomerization product was 50 ~AZEN.
EXAMPLE 6 (Co~rArison) ~retdione- and isocyanurate-contA;ning EDI
prepared according to Example 2, was stored under nitro-gen for 6 months at 50~C after the monomeric HDI had been separated off. The visco~ity increased during this - period from 2,460 mPa.s at 25~C to 5,870 mPa.s at 25~C.
The color index of the product remained consta~t at 30 HAZEN.
300 ppm of 3-chloroperbenzoic acid were added to 212~
. ~.
- 9 - O.Z. 0050/44130 the uretdione- and isocyanurate-conta~nin~ EDI used in Example 6, after the monomeric HDI had ~een separated off. I~e product treated in thi~ manner was ~tored at 50~C under nitrogen for 6 months. The ~isco~$ty of the i S product increased from 2,460 mPa.~ at 25~C to 2,920 mPa.s at 25~C and the color index remained constant at 10 The ~AZEN color index was determ~ne~ according to DIN 53,995.
For high quality one-component and two-component polyurethane finishes having high light stability and weather stability, the isocyanate components used are in particular isocyanurate- and uretdione-conta~n~ng poly-isocyanate mixtures.
These products are preferably prepared by catal-ytic oligomerization of aliphatic and/or cycloaliphatic diisocyanates, eg. 1-isocyanato-3,3,5-trimethyl-5-iso-cyanatomethylcyclohexane (IPDI) orl,6-diisocyanatohe~Ane (HDI).
The catalysts used may be, for example, hydrox-ides or organic salts of weak acids having tetraalkyl-ammonium groups, hydroxides or organic salts of weakacids having hydroxyalkylammonium groups, alkali metal salts or tin, zinc or lead salts of alkanecarboxylic acids.
The aliphatic and/or cycloaliphatic diisocya~ates are allowed to react i~ the presence of the catalyst, with or without the use of solvents and/or assistants, until the desired conversion has been reached. There-after, the reaction is stopped by deactivating the catalyst and the excess mon~e~ic diisocyanate 18 dis-tilled off. Depending on the catalyst type used and onthe reaction temperature, polyisocyanates having dif-ferent contents of isocyanurate and uretdione groups are ~1 2~,?8 ,:-1 - ~ - 2 - O.Z. 0050/44130 obtained.
The products thus prepared are generally clear products wh$ch,~however, depsn~;n~ on the catalyst type, the diisocyanate guality, the reaction temperature and the reaction procedure, are more or less strongly yellow.
~ owever, products having a very low color index are desirable for the production of high quality poly-urethane finishes. The prior art discloses a number o~
methods for reducing tho color index of such products.
For example, DE-A-38 06 276 proposes reducing the carbon dioxide content of the HDI used as a monomer to less than 20 ppm before the oligomerization by degassing under reduced pressure and subsequently blowing nitrogen through the HDI, and using a quaternary ammonium hydrox-ide as the oligomerization catalyst. The process step of carbon dioxide removal is, however, technically very complicated.
EP-A-0 339 396 proposes the use of a quaternary ~on; um fluoride as a trimerization catalyst. In this process, a higher carbon dioxide content can be tolerated but the proposed catalyst must be chemically deactivated.
The resulting compounds remain in the product and may give ri~e to problems with performance characteristics during further processing. A further possibility for the preparation of isocyanurate-containing polyisocyanates having a lower color index is to add polyesterdiols to the starting diisocyanate, as proposed in EP-A-0 336 205.
This makes it possible to reduce the amount of catalyst u~ed. ~owever, the resulting products still have a relatively strong color.
In EP-A-0 377 177, the aliphatic diisocyanate is oligomerized in the presence of a phosphine as a catal-yst, and the unconverted diisocyanate is partly distilled off after the oligomerization has been stopped and partly converted into urethane by the addition of alcohol. The reaction product is then treated with peroxides.
Although the peroxide treatment results in a reduction in th~ color index of the oligomerization product, the use of peroxldec often gives riso to problem~. For example, peroxides aro technically dlfficult to h~n~le. Perox~des which aro safer to handlo are generally availablQ in solution, dibutyl phthalate, ~requently used as a sol-vent, then leading to pro~lems with the performance characteri~tics dur~ng production o~ the fin~h.
A ~urther substantial disad~antage of the prio~
art process i8 that the shelf life of the product~ thus o obtained i8 insufficient. The color properties deter~or-ato and in part~cular ther~ i8 a substantial increase in the ~i~cosity.
It iB an ob;ect of th~ present invention to pro~ide a simple proces~ for th~ preparation of i~ocyanurate- and/or uretdione-cont~n~ng polylsocyanates ha~ing a reduced color index, which proces~ a~oids the disadvantage~ of the prior art and in parti~ular lQads to products having an improved shel~ life.
In accordance with the invention, this object is 20 surprisingly achieved by a process for the preparation of an isocya-nurate- or uretdione-containing polyisocyanate having a reduced color index and improved shelf life comprising oligomerization of aliphatic or cycloaliphatic diisocyanates using oligomerization catalysts comprising hydroxides or organic salts of acids having tetraalkylammonium or hydroxy-alylammonium groups, alkali metal salts, or tin, zinc, or lead salts of alkanecarboxylic acids, and subsequently neutralizing said oligomerization catalyst with a peroxycarboxylic acid.
The present invention furthermore relates to the 30 isocyanurate- and/or uretdione-containing polyisocyanates having a reduced color index and prepared by this process.
When basic, in particular amine, oligomerization catalysts are used, peroxycarboxylic acids are added to deactivate the catalyst when the desired degree of oligomerization has been reached, and the oligomerization - 3a -product is then worked up in the conventional manner used in the prior-art, by removal of monomers, generally under greatly 212~85 4 - O.Z. 0050/44130 evaporator. A special process step for lightening the oligomerization products is then no longer required.
The oligomerization of the aliphatic and/or the cycloaliphatic diisocyanates i8 carried out by the method S usual ln the prior art.
The starting diisocyanates used are aliphatic and/or cycloaliphatic diisocyanates, eg. 1,4-diiso-cyanatohexane, 1,6-diisocyanatohexane (EDI), 1,12-diiso-cyanatododecane, l-isocyanato-3,3,5-trimethyl-5-iso-cyanatomethylcyclohexane (IPDI), 4,4'-di~socyanato-dicyclohexylmethane, 1,5-diisocyanato-2,2-dimethyl-pentane, 1,5-diisocyanato-2-ethyl-2-propylpentane, 1,6-diisocya~ato-2,4,4-trimethylhexane and l,S-diisocyanato-2-methylpentane, in particular EDI.
The oligomerization of the diisocyanates is preferably carri-d out at from 0 to 100~C by passing through inert gas, preferably nitrogen. The reaction rate is too low at lower temperatures, while the level of secondary reactions is greater at higher temperatures.
The catalysts used may be any catalysts suitable for the oligomerization of aliphatic and/or cyclo-aliphatic diisocyanates, for example hydroxides or organic salts of weak acids having tetraalkylammonium groups, hydroxides or organic salts of weak acids having hydroxyalkyl~ -n;um groups, alkali metal salts or tin, zinc or lead salts of alkanecarboxylic acids. The catalysts are usually used in an amount of from O.OS to 2% by weight, based on the diisocyanate.
To reduce the amount of catalyst, it is possible to add a small amount, up to about 1% by weight, based on the diisocyanate, of a diol, in part~cular a polyester-diol, to the diisocyanates in a manner ~nown per se, prior to oligomerization.
Thereafter, the diisocyanatQ is brought to the reaction temperature with stirring and the catalyst i8 slowly added. To improve the handling, the catalyst may be dissolved in a solvent. For example, alcohols, in 212~2~5 ~- - 5 - O.Z. 0050/44130 particular diols, ketono~, ethers and esters are suitable for this purpose.
After the desired conversion has been reached, the reaction is stopped by deactivation of the catalyst, for example by the addition of a catalyst poison or by thermal decomposition of the catalyst. The reaction mixture iB then freed from the monomeric diisocyanates in a suitable manner known per se, for example by distilla tion, eg. by means of a thin-film evaporator.
A particularly advantageous and therefore prefer-red e~hodiment of the invention comprise~, as stated above, using the peroxycarboxylic acids as neutralizing agentJ for the basic oligomerization catalysts employed.
The novel peroxycarboxylic acids are added to the reac-tion mixture in an amount of from 10 to 10,000 ppm, prefer~bly from 50 to 1,000 ppm, based on the reaction mixture, when the desired degree of oligomerization has been reached, in order to deactivate tho catalyst and hence to stop the reaction. The peroxycarboxylic acids may al~o be used together with conventional neutralizing agents. The reaction mixture is then freed from the monomeric diisocyanates in a suitable manner known per se, for example by distillation, eg. by means of a thin-film evaporator.
For the purposes of the present invention, it is, however, also possible to deactivate the catalyst in another suitable manner, for example by means of catalyst poisons or by thermal decomposition, when the desired degree of oligomerization has been reached. The reaction mixture i8 then freed from the monomeric diisocyanates in the manner described. The novel peroxycarboxylic acids are added in an amount of from 10 to 10,000 ppm, prefer-- ably from 50 to 1,000 ppm, based on the amount of diiso-cyanate, to the solution worked up in this manner.
The peroxycarboxylic acids used may be aromatic, aliphatic, cycloaliphatic, unsubstituted or substituted peroxycarboxylic acids. It is also possible to use 8 ~
_ - 6 -acidic salts of these peroxycarboxylic acld~.
Examples of peroxycarboxylic acids aro peracetic acid, peroxymaleic acld, tert-butyl peroxymaleia acld, perbenzoic acid, p-nitroperbenzoic acid peroxyphthalic a~
and in particular 3-chloroperbenzoic acid. Ammonium or magne~lum ~alt~ are used in partiaular as acldic salt~ o~
the peroxycarboxylia acid~.
ThR no~cl process ~or the preparatlon of i80-cyanurate- and/or uretdione-cont~n~ng polyisocyanatQ~
lQads to products having low color lndices. Th~ color lndlce~ are below 50 HAZEN but generally below 30 ~A~EN.
~owe~er, the particular advantago o~ the product~ pre-pared according to the lnvention is thelr very good shel~
li~e. Even after a storage! timQ o~ 6 month~ under a nltrogen atmosphere, there was no change in the color, and furthermore the iLcrea~e in the ~scoslty of these products was corre~ponding smaller than ~n the case of those which had been prepared by the prior art processe~.
An addit~onal ad~antageous ef~ect occurred 1~ the neutralization of tho oligomerization catalyst with peroxycarboxyl~c acld~. Here, the monomeric diisocyanate dlstilled o~f after the oligomerization o~ the al~phatic and/or cycloallphatic diisocyanates did not exhibit the disad~antage~ otherwise ~requently encountered in the ca~e o~ the corre~ponding products o~ the~ prlor art processen.
While, in thQ nQutralization o~ tho ollgomQriza-tion catalyst with the al~yl phosphate~ generally used 1~
the prior art proce~se~, the reactivlty o~ the recycled di~socyanate monomers wa~ substantlally lower than that o~ fresh diisocyanate and it i~ there~ore nece~sary ~o use a larger amount o~ cataly~t, the monomerlc dilso-cyanate recycled in the neutralization of the ol~gomerlz-ation catalyst with peroxycarboxyliQ acid~ exhlblted no such behavior and could be readily ol~gomQr~zQd unde~ the con~entional proce~s conditione and wlth the U8Q o~ the u~ual amount o~ ca~alyst.
2~'~62~5 - 7 - O.Z. 0050/44130 _ In the thermal decomposition of the oligomeriza-tion product, likewise known from ths prior art, the recycled monomer$c diisocyanate generally exhibits no differences in reactivity compared with fresh diiso-cyanato, but gelling of these products freguently occurs.
Furthermore, such behavior was not observed in the case of ths mon~ric diisocyanate8 obtained by the novel process.
The novel products are generally used a~ iso-cyanate components in polyurethane one-component and two-component finishes.
The Examples which follow illustrate the invention.
EXAMPLE 1 (Cn~rarison) 500 g of 1,6-diisocyanatohexane (EDI) were heated to 80~C under a nitrogen blanket, and 400 ppm of N,N,N-trimethyl-N-(2-hydroxypropyl)-a onium 2-ethylhexanoate, dissolved in 2 ml of methyl ethyl ketone (MER), were added while stirring.
When the NC0 content of the reaction mixture was 43% by weight, 2 mol eguivalents, based on tho amount of catalyst, of dibutyl phosphato were added and stirring was continued for 1 hour at 80~C. ~nconverted ~DI was then stripped off under greatly reduced pressure by means of a thin-film evaporator.
The color index of the oligomerized EDI was 78 HAZEN. 400 ppm of N,N,N-trimethyl-N-(2-hydroxypropyl)-a on; um 2-ethylhexanoate were then added, while stir-ring, to 250 g of the monomeric HDI stripped off. No decrease in the NC0 content was observed.
EXAMPLE 2 (Comparison) The procedure was as in Example 1, except that the reaction mixture was heated for 15 minutes at 110~C
to deactivate the catalyst.
The mon~ ~ric ~DI stripped off had a normal reactivity but gelled on stan~ing in a closed vessel under nitrogen at 5~C.
~2~2~
8 - O.Z. 0050/44130 EXAMPL~ 3 The procedure was as in Example 1, except that 2 mol equivalents, based on the catalyst, of 3-chloro-perbenzoic acid were used to neutralize the catalyst.
The color $ndex of the oligomerization product was 25 EAZEN. 400 ppm of N,N,N-trimethyl-N-(2-hydroxy-propyl) _r ~n~ um 2-ethylhexanoate, dissolved in 2 ml of MER, were added at 80~C to 200 g of the monomeric HDI-stripped off.
The decrease in the NCO content was the same as for fresh ~eno~ric HDI. When an NCO content of 43% by weight, based on the reaction mixture, had been reached, the catalyst wa~ neutralized by D~ ng 2 mol equivalents of 2-chloroperbenzoic acid. The oligomerization product had a color index of 20 EAZEN. 50 g of the monomeric HDI
stripped off were stored at 5~C for 4 weeks under nitrogen in a closed vessel. No gel formation occurred.
The procedure was as in Example 1, except that 2 mol equivalents of 4-nitroperbenzoic acid were used to neutralize the catalyst. The color index of the oligo-merization product was 27 HAZEN.
The procedure was as in Example 1, except that 2 mol equivalents of magnesium monoperoxyphthalate were used to neutralize the catalyst. The color index of the oligomerization product was 50 ~AZEN.
EXAMPLE 6 (Co~rArison) ~retdione- and isocyanurate-contA;ning EDI
prepared according to Example 2, was stored under nitro-gen for 6 months at 50~C after the monomeric HDI had been separated off. The visco~ity increased during this - period from 2,460 mPa.s at 25~C to 5,870 mPa.s at 25~C.
The color index of the product remained consta~t at 30 HAZEN.
300 ppm of 3-chloroperbenzoic acid were added to 212~
. ~.
- 9 - O.Z. 0050/44130 the uretdione- and isocyanurate-conta~nin~ EDI used in Example 6, after the monomeric HDI had ~een separated off. I~e product treated in thi~ manner was ~tored at 50~C under nitrogen for 6 months. The ~isco~$ty of the i S product increased from 2,460 mPa.~ at 25~C to 2,920 mPa.s at 25~C and the color index remained constant at 10 The ~AZEN color index was determ~ne~ according to DIN 53,995.
Claims (19)
1. A process for the preparation of an isocyanurate- or uretdione-containing polyisocyanate having a reduced color index and improved shelf life comprising oligomerization of aliphatic or cycloaliphatic diisocyanates using oligomerization catalysts comprising hydroxides or organic salts of acids having tetraalkylammonium or hydroxyalylammonium groups, alkali metal salts, or tin, zinc, or lead salts of alkanecarboxylic acids, and subsequently neutralizing said oligomerization catalyst with a peroxycarboxylic acid.
2. A process as claimed in claim 1, wherein the starting diisocyanate is 1,6-diisocyanatohexane.
3. A process as claimed in claim 1, wherein the peroxycarboxylic acid is used for deactivating the oligomerization catalyst.
4. A process as claimed in claim 1, wherein unconverted monomeric diisocyanates are removed from the oligomerization product, and the peroxycarboxylic acid is added to the oligomerization product after the removal of the unconverted monomeric diisocyanates.
5. A process as claimed in claim 1, wherein the peroxycarboxylic acid is used in an amount of from 10 to 10,000 ppm, based on the diisocyanate used.
6. A process as claimed in claim 1, wherein the peroxycarboxylic acid is used in an amount of from 50 to 1,000 ppm, based on the diisocyanate used.
7. The process of claim 1, comprising oligomerizing a reaction mixture of catalyst and aliphatic or cycloaliphatic diisocyanates, adding the peroxycarboxylic acid to the reaction mixture when the desired degree of oligomerization is obtained, and subsequently removing unreacted monomeric diisocyanates from the reaction mixture.
8. The process of claim 7, wherein from 10 to 10,000 ppm of peroxycarboxylic acid are added, based on the weight of the reaction mixture.
9. The process of claim 8, wherein the amount of peroxycarboxylic acid is from 50 to 1,000 ppm.
10. The process of claim 1, comprising oligomerizing a reaction mixture of catalyst and aliphatic or cycloaliphatic diisocyanates to the desired degree of oligomerization, removing unreacted monomeric diisocyanates, and subsequently adding peroxycarboxylic acid.
11. The process of claim 10, wherein the amount of peroxycarboxylic acid added is from 10 to 10,000 ppm based on the amount of diisocyanates used.
12. The process of claim 11, wherein the amount of peroxycarboxylic acid is from 50 to 1,000 ppm.
13. The process of claim 1, wherein the peroxy-carboxylic acids comprise peracetic acid, peroxymaleic acid, tert-butyl peroxymaleic acid, perbenzoic acid, p-nitrobenzoic acid, peroxyphthalic acid, 3-chloroperbenzoic acid, or salts thereof.
14. The process of claim 13, wherein the salts comprise magnesium or ammonium salts of the acids.
15. The process of claim 13, wherein the acid comprises 3-chloroperbenzoic acid.
16. The process of claim 1, wherein the isocyanurate- or uretdione-containing polyisocyanate has a color index below 50 HAZEN.
17. The process of claim 16, wherein the color index is below 30 HAZEN.
18. The process of claim 1, wherein the isocyanurate- or uretdione-containing polyisocyanate does not change color at six months of storage under a nitrogen atmosphere.
19. An isocyanurate- and uretdione-containing polyisocyanate having a reduced color index, when prepared by a process as claimed in any one of claims 1 to 18.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4320821A DE4320821A1 (en) | 1993-06-23 | 1993-06-23 | Process for the preparation of polyisocyanates containing isocyanurate and / or uretdione groups with a reduced color number and improved storage stability, and products produced by this process |
| DEP4320821.5 | 1993-06-23 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2126285A1 CA2126285A1 (en) | 1994-12-24 |
| CA2126285C true CA2126285C (en) | 1998-12-22 |
Family
ID=6491000
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002126285A Expired - Fee Related CA2126285C (en) | 1993-06-23 | 1994-06-20 | Preparation of isocyanurate-and/or uretdione-containing polyisocyanates having a reduced color index and improved shelf life, and products prepared by this method |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5436336A (en) |
| EP (1) | EP0630928B1 (en) |
| JP (1) | JP3642583B2 (en) |
| CA (1) | CA2126285C (en) |
| DE (2) | DE4320821A1 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5691440A (en) * | 1995-10-05 | 1997-11-25 | Arco Chemical Technonogy, L.P. | Catalyst and process for producing isocyanate trimers |
| DE19758050A1 (en) * | 1997-12-29 | 1999-07-01 | Huels Chemische Werke Ag | Process for producing a color-reduced isocyanate group-containing polyisocyanate based on 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI) |
| DE19828935A1 (en) * | 1998-06-29 | 1999-12-30 | Basf Ag | High viscosity polyisocyanate composition useful as a surface coating |
| FR2818974B1 (en) * | 2000-12-29 | 2003-10-24 | Rhodia Chimie Sa | (CYCLO) CONDENSATION OF ISOCYANATE COMPOUNDS |
| KR100947647B1 (en) * | 2001-03-27 | 2010-03-15 | 로디아 쉬미 | Low-viscosity polyisocyanate composition of high functionality and preparation process therefor |
| FR2822828B1 (en) * | 2001-03-27 | 2005-04-15 | Rhodia Chimie Sa | LOW VISCOSITY POLYISOCYANATE COMPOSITION HAVING HIGH FUNCTIONALITY AND PROCESS FOR PREPARING THE SAME |
| DE102004012571A1 (en) * | 2004-03-12 | 2005-09-29 | Basf Ag | Process for the preparation of polyisocyanates containing isocyanurate groups and their use |
| DE102005006550A1 (en) * | 2005-02-11 | 2006-08-24 | Basf Ag | Process for the preparation of polyisocyanates and their use |
| JP5650119B2 (en) * | 2008-10-22 | 2015-01-07 | ビーエーエスエフ ソシエタス・ヨーロピアＢａｓｆ Ｓｅ | Method for producing colorless polyisocyanate |
| DE102009005712A1 (en) * | 2009-01-22 | 2010-07-29 | Bayer Materialscience Ag | Polyurethanvergussmassen |
| CN110372846B (en) * | 2019-07-15 | 2021-06-25 | 万华化学集团股份有限公司 | Preparation method of polyisocyanate with stable color value and containing uretdione group |
| EP4107198B1 (en) | 2020-02-17 | 2024-03-13 | Covestro Deutschland AG | Polyisocyanate preparations |
| CN112250835B (en) * | 2020-09-14 | 2022-03-11 | 万华化学（宁波）有限公司 | Method for preparing colorless polyisocyanate composition |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3900053A1 (en) * | 1989-01-03 | 1990-07-12 | Bayer Ag | PROCESS FOR THE PREPARATION OF POLYISOCYANATES USING URETDION AND ISOCYANATE GROUPS, THE POLYISOCYANATES AVAILABLE FOR THIS PROCESS, AND THEIR USE IN TWO-COMPONENT POLYURETHANE VARNISHES |
| DE4033288A1 (en) * | 1990-10-19 | 1992-04-23 | Bayer Ag | METHOD FOR PRODUCING POLYISOCYANATES HAVING URETDION AND / OR ISOCYANURATE GROUPS, THE POLYISOCYANATES OBTAINED BY THIS METHOD AND THEIR USE IN POLYURETHANIC PAINTS |
-
1993
- 1993-06-23 DE DE4320821A patent/DE4320821A1/en not_active Withdrawn
-
1994
- 1994-05-27 JP JP11496094A patent/JP3642583B2/en not_active Expired - Fee Related
- 1994-06-13 EP EP94109017A patent/EP0630928B1/en not_active Expired - Lifetime
- 1994-06-13 US US08/259,105 patent/US5436336A/en not_active Expired - Lifetime
- 1994-06-13 DE DE59404388T patent/DE59404388D1/en not_active Expired - Lifetime
- 1994-06-20 CA CA002126285A patent/CA2126285C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US5436336A (en) | 1995-07-25 |
| EP0630928A3 (en) | 1995-03-15 |
| DE59404388D1 (en) | 1997-11-27 |
| JPH07138343A (en) | 1995-05-30 |
| EP0630928B1 (en) | 1997-10-22 |
| EP0630928A2 (en) | 1994-12-28 |
| DE4320821A1 (en) | 1995-01-05 |
| CA2126285A1 (en) | 1994-12-24 |
| JP3642583B2 (en) | 2005-04-27 |
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